1. Field of Invention
The present disclosure relates in general to injecting fluid into a well, and in particular to methods and devices that blend additives to the fluid in an eductor.
2. Description of Prior Art
Fluids are often injected into wells during various wellbore operations, such as during drilling, pump down procedures, or hydraulic fracturing (“fracing”). A blender is typically provided at the well site during the fracing process for mixing chemicals, water, and proppant. The chemicals generally include friction reducers and viscosity enhancers. The blender feeds the mixture to high pressure pumps for pressuring the mixture to pressures that often approach 10,000 psi; the pressurized mixture is then injected into the well to create fractures.
Completion of a well typically involves perforating through casing that lines the wellbore, where perforating generally starts at a lowermost depth in the wellbore, and is sequentially performed at reduced depths up the wellbore. Plugs are generally installed in the wellbore above each set of perforations. It is not uncommon for an operator to create twenty or more sets of perforations, and install twenty or more plugs in a well. The plugs are usually removed with a drilling system. High pressure completion drilling fluid is often circulated through the wellbore while the plugs are being drilled. Typical drilling pressures are in the range of 2500 to 5000 psi, and the flow rates are usually at least 100 gpm (gallons per minute). The fluid flow rate and pressure is controlled so that the drilled plug fragments flow out of the wellbore entrained within the completion drilling fluid. To enhance the flow of the completion drilling fluid, friction reducers, chemicals, or viscosifiers such as liquid gelling agents are added to the well fluid in a blender. The friction reducers and viscosifiers are normally polymers. After a designated viscosity has been reached, the drilling fluid is directed from the blender to the high pressure pumps. Blending can be time consuming, which adds to the total time to drill out the wells containing the temporary frac plugs.
Mixing devices and systems such as low, or zero, pressure surface blending systems, low pressure batch mixing systems, low pressure surface hydration systems and other such systems primarily depend on time. Conventional blenders use atmospheric tanks, static mixers, internal stirring paddles, and/or some form of non-positive suction and/or displacement high pressure jetting. The blending unravels and shear stresses component molecules of the chemicals being introduced. Blending is done in efforts to bring multiple components ultimately into one homogeneous and consistent blend of quality product with enhanced chemical and physical characteristics. Atmospheric blending generally requires at least two hours to achieve hydration rates of around 90%.